Apparatus For Sighting-In A Gun

ABSTRACT

To sight-In a gun—especially a rifle ( 10 )—it has to be held in the same position while it is fired at least twice, the gunsight ( 14 ) being adjusted after the first shot so that the gun sight shows the gun aimed at the point of impact of the first shot on the target. Apparatus to hold the gun while sighting-in is performed has a base ( 16 ) on which an elogate support frame ( 40 ) is mounted. The support frame ( 40 ) carries a rear stock clamping arrangement, with which clamping members ( 21 ) firmly hold the rear stock ( 11 ) of the gun. A gun barrel ( 13 ) or front stock ( 12 ) locating arrangement ( 30,31,32,34,37,39 ), also carried by the support frame, ensures that the front stock (or barrel) of the gun can be repositioned (if it has not been clamped) in the same position after a shot has been fired. Mounting blocks ( 115, 116 ) clamped to the base ( 16 ) include means to make fine adjustments of the lateral pointing of the gun. Course variation of the vertical pointing of the gun is effected by changing the height above the support frame ( 40 ) of a horizontal bar ( 30 ) of the front stock locating arrangement. Fine adjustment of the vertical pointing of the gun is effected by movement of pivot arms ( 24 ), on which the rear stock clamping members ( 21 ) are carried, about a pivot axis ( 27 ). Straps to prevent or limit gun movement due to recoil may be included.

TECHNICAL FIELD

This invention concerns guns. More particularly, it concerns the sighting-in of rifles and pistols (whether using rim fire or centre fire cartridges), shotguns, pneumatic rifles and other hand-held guns. The term “sighting-in of a gun” means the adjustment of the sighting system of the gun so that the accuracy with which any bullet, shell or quantity of shot, that has been fired from the gun, arrives at the intended target is optimised.

BACKGROUND TO THE INVENTION

On a rifle range or pistol range, knowledge of the accuracy of a rifle, shotgun or pistol is necessary if a shooter is to determine where to aim to hit a target (or to group shot on a target in the case of a shotgun). Acquiring that knowledge has been a problem for many years. All manufacturers of firearms perform some sighting-in of the guns they manufacture, but each owner of a gun has to work out, independently, how to aim the gun to have the best chance of success.

In the specification of Australian patent application No. 15404/02, entitled “Apparatus and method for calculating aiming point information for rifle scopes”, the factors that contribute to inaccuracy in aiming a gun are outlined. The proposals for improving aiming that are found in the specifications of U.S. Pat. Nos. 1,190,121 (to Critchett), 3,948,587 (to Rubbert), 3,492,733 (to Leatherwood) and 4,403,421 (to Shepherd) are discussed and the reasons for the failure of those proposals are noted. After this discussion, a reticule for a telescopic gun sight which can be calibrated automatically by using a hand-held electronic ballistics calculator is described. The hand-held electronic ballistics calculator is a computer containing a ballistics program which uses data (including some or all of temperature, wind speed and wind direction, barometric pressure, relative humidity and the slope of the ground over which a bullet will be fired) to align the novel reticule for accurate marksmanship. When the result of the aiming of the rifle is known, the ballistics calculator indicates the changes in the set-up parameters that are needed to improve the aiming of the rifle.

The device of patent application No. 15404/02, however, appears to be designed for use by hunters, who need to shoot over long distances. In addition, the setting up of the device requires knowledge that is often not available, and the parameters selected (especially wind speed and wind direction) can vary significantly in a very short time.

DISCLOSURE OF THE INVENTION

Preliminary note: In this specification, “directional” terms (such as “top”, “bottom”, “upper”, “lower”, “front”, “back”, “rear”, “above”, “below”, “vertical”, “horizontal” and “side”) will be used in the sense that they would have with reference to an embodiment of the invention positioned as shown in FIG. 1 of the accompanying drawings.

It is an objective of the present invention to provide apparatus which enables a shooter to perform sighting-in of a gun, particularly a gun to be used in ranges over predetermined distances from the rifle to the target of up to 1,000 metres, and even over more than 1,000 metres.

This objective is achieved by providing apparatus that can be used with a rifle, shotgun or pistol having any conventional type of gun sight. This apparatus comprises a generally elongate support frame, having a front end and a back end at opposite ends of the elongate direction of this frame. A front stock (or barrel) locating means is mounted at or near the front end of the support frame, and a rear stock clamping means is mounted at or near the back end of the support frame.

The support frame itself is mounted on a pair of base connection blocks (a front connection block and a back connection block) that are adapted to be clamped to a base. The base may be any heavy, stable structure of metal, wood or other rigid material (for example, a purpose-built concrete block). The important characteristic of the base is that has a high mass compared with the gun, and that it is not affected by the recoil that is experienced when the gun is fired.

The front stock (or barrel) locating means comprises a rigid horizontal bar mounted on the support frame, with the elongate direction of the horizontal bar being transverse the elongate direction of the support frame. Locating means, typically a pair of locating members in the form of blocks, which may have pads attached to their opposed surfaces and which are moveable along the top of this horizontal bar, ensures that the front stock (or barrel) is positioned as required above this bar. The positions of these blocks on the horizontal bar may be controlled by respective block moving means, supported on or close to an end of the horizontal bar. Alternatively, the blocks may be manually located in their required positions on the bar, and then be clamped to the bar in those required positions. When the invention is in use, the front stock (or the barrel) of the gun rests on the top surface of the horizontal bar (that top surface being preferably covered, at least over its central region, with a layer of a rubber material, neoprene, or a suitable plastics material) and the locating blocks are moved until each block bears against a respective side of the front stock (or barrel) of the gun. Normally, the locating blocks in this position will not clamp the front stock (or barrel) of the gun, but individual shooters may use these blocks as a clamping device. In the following description, it will be assumed that these locating blocks do not clamp the front stock or barrel of the gun.

The rear stock clamping means includes a pair of clamping members, each of which has a substantially vertical surface that is opposed to the vertical surface of the other clamping member (in other words, the substantially vertical surfaces are mutually opposed). The clamping members are adapted to be moved laterally relative to the elongate direction of the support frame, so that the vertical surfaces contact the side faces of the rear stock of the rifle or shotgun (or the side faces of the handle of a pistol). Preferably, these clamping members are mounted on bearings for rotation about respective horizontal axes, which are at right angles to the substantially vertical surfaces of the clamping members. These axes of rotation are substantially co-linear.

With such front stock (or barrel) locating means and rear stock clamping means, when a gun that is being sighted-in is fired, the recoil effect of firing the gun causes the gun barrel to lift and the entire gun to be rotated (by an amount which is dependent on the strength of the recoil effect) about the axes of rotation of the rear stock clamping members. However, the lateral positions of the locating pads on the horizontal bar should not change during this rotation of the gun and, since neither rear stock clamping member moves laterally, after the recoil effect, the gun can be relocated in precisely the same position on the support frame that it had before the gun was fired.

Embodiments of the invention will also include gun tilting means, to raise or lower the horizontal bar of the front stock (or barrel) locating means relative to the top of the support frame, and/or to raise or lower the rear stock clamping members relative to the top of the support frame, and, thereby, to lower or raise the front of the barrel of the gun relative to its rear stock (if a rifle) or its handle (if the gun is a pistol).

Thus the present invention provides apparatus for use in the sighting-in of a gun, said gun having a barrel, a rear stock and (if the gun is a rifle) a front stock; said apparatus comprising:

-   a) a generally elongate support frame having a front end and a back     end; -   b) a base on which said support frame is mounted; -   c) front stock (or barrel) locating means mounted on said support     frame at or near the front end thereof; said front stock (or barrel)     locating means comprising a horizontal bar supported above, and     extending in a direction transverse to the elogate direction of said     support frame, and restraining means mounted on said bar to prevent     sideways movement of said front stock (or barrel); -   d) rear stock clamping means mounted on said support frame at or     near the back end thereof; said rear stock clamping means comprising     a pair of stock clamping members, each stock clamping member having     a substantially vertical surface which is opposed to the     substantially vertical surface of the other stock clamping member;     each stock clamping member being adapted to be moveable laterally     relative to the elongate direction of the support frame, so that,     when the sighting-in apparatus is in use, said vertical surfaces may     be moved to contact respective side faces of the rear stock of a     rifle or a shotgun, or to contact respective side faces of the     handle of a pistol or similar gun, which is mounted on said     apparatus; each said stock clamping member being mounted on a     respective horizontal clamping member support, which is     substantially at right angles to the substantially vertical surfaces     of the clamping members; and -   e) gun tilting means for raising or lowering the rear stock clamping     members relative to the top of the support frame, thereby to lower     or raise the front of the barrel of the gun relative to its rear     stock (if a rifle) or its handle (if the gun is a pistol).

Embodiments of the invention, including these and other features of the present invention (some being optional features) will now be described, by way of example only. In the following description, reference will be made to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly schematic side view of one form of gun sighting-in apparatus constructed in accordance with the invention, mounted on a base, with a rifle in position on the apparatus.

FIG. 2 is a side view of a prototype of the invention.

FIG. 3 is a perspective sketch of the front and rear mounting blocks used, in the prototype apparatus shown in FIG. 2, to connect the support frame to a base.

FIG. 4 is a plan view, from below, of the prototype apparatus of FIG. 2.

FIG. 5 is a plan view, from above, of the prototype apparatus of FIG. 2, but with some of the mechanisms for mounting the support frame on the base omitted, for clarity.

FIG. 6 is a partly schematic perspective sketch of the stock clamping means of the prototype apparatus, mounted on the support frame.

FIG. 7 is a partly schematic perspective sketch of the front stock (or barrel) locating means of the prototype apparatus shown in FIG. 2.

FIG. 8 is a view, from the front, of part of the front stock (or barrel) locating means shown in FIG. 7.

FIG. 9 shows two alternative constructions of the support frame of the present invention.

FIG. 10 depicts one alternative form of mounting block that may be used instead of the mounting block 116 shown in FIG. 3.

FIG. 11 is a partly schematic perspective sketch of another alternative form of mounting block, which may be used instead of the mounting block 115 shown in FIG. 3.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 shows a rifle 10 having a rear stock 11 which extends to a front stock 12. This rifle has a barrel 13. A telescopic sight 14 is mounted on the rifle 10. The rear stock (sometimes called the butt stock) 11 of the rifle 10 is held firmly by a pair of clamping members 21 of a stock clamping means mounted on a support frame 40. The front stock 12 (or the barrel 13) is located between a pair of pads 31 of a front stock (or barrel) locating means, which is also mounted on the support frame 40.

The support frame 40 is held firmly on a pair of mounting blocks 115 and 116 which are clamped to a base 16. Normally, the front mounting block 115 is the first mounting block to be clamped onto the base 16 and the rear mounting block 116 is then moved fore and aft until it is located in a required (or an appropriate) position, prior to its clamping onto the base 16.

In a prototype of the invention, constructed by the inventor, the support frame 40 comprises a pair of parallel, elongate, spaced apart, square-section side members 41, connected to each other by two spaced apart, short, transverse square-section transverse members 42. (More than two transverse members may be included in a support frame.) Both the side members 41 and the transverse members 42 of the prototype apparatus are made of steel, and the ends of the transverse members are welded to the inside vertical walls of the side members 41. However, it will be appreciated that the side members 41 need not be parallel to each other (although this will usually be the case) and the transverse members 42

-   a) need not have a square or rectangular cross-section, -   b) can be constructed of materials other than steel, -   c) may not be welded to each other but, instead, may be rigidly     connected to each other using other known methods and materials, and -   d) may be solid or hollow.

The support frame 40 shown in FIG. 1 is constructed of two sub-frames which have side members which are parallel to each other and which

-   (a) in part, fit telescopically, one within the other; or -   (b) are slidable over a central frame support rod (rod 141 in FIG.     1).

Apertures 46 and 47 are provided, respectively, in the side members 40 and the central frame support rod 141, so that the support frame can be lengthened or shortened as required, with associated pins, bolts or other suitable retaining means being inserted into aligned apertures 46 and 47 to locate the side members in a required position before they are clamped using clamps 48. If the side members can be substantially shortened, the same equipment may be able to be used for sighting-in pistols, rifles and shotguns. If the side members cannot be shortened sufficiently, or cannot be shortened at all, rifles and shotguns of similar, but different, lengths will normally be able to be sighted-in using the apparatus, but a separate support frame will be required for sighting-in a pistol.

The front mounting block 115 shown in FIG. 3 is designed to enable the support frame to be mounted securely on the base 16. In the prototype equipment that has been constructed by the inventor, this mounting block comprises an elongate transverse block member, in the form of a length of rectangular steel tubing 50, on to which are welded

-   (1) a central cradle, into which a transverse member 42 of the     support 40 may be positioned, this central cradle comprising a     horizontal plate 51 and a pair of upright (vertical) planar plates     52 and 53, each with an associated position adjustment and clamping     screw 54, which is controlled by a “handle” 59; -   (2) a lower horizontal plate 55 containing a slot or an aperture 56,     through which a bolt can be extended (or through which a bolt     extending from the base 16 may pass) to enable this lower horizontal     plate to be clamped to the base 16; and -   (3) a pair of vertical side flanges (planar plates) 57 with     associated adjusting/clamping screws 58.

The spacing of the side flanges 57 is such that the side members 41 of the support frame 40 are a loose fit between the flanges 57, and the adjusting/clamping screws 58 can be used to adjust—in a limited way—the lateral position of the support frame and then clamp the support frame in its required lateral position.

The rear mounting block 116 is similar to the front mounting block 115, comprising a length of rectangular steel tubing 150 on to which are welded a pair of vertical side flanges 157 with associated adjusting/clamping screws 158. However, the cradle arrangement consisting of the horizontal plate 51 and the vertical flanges 52 and 53, with their associated clamping/adjusting screws 54, is omitted. This omission enables the rear mounting block 116 be moved to different locations on the base if (a) the length of the support frame 40 is adjustable, and/or (b) the length of the base 16 is limited.

The lower horizontal plate members 55 and 155 of the front and rear mounting blocks 115 and 116 are secured to the base 16, typically by bolts which pass upwardly from, or downwardly into, the base 16 through the respective slots 56 and 156 in the plate members 55 and 155. Respective nuts are tightened onto the bolts that pass upwardly from the base 16 through the slots or apertures 56 and 56B; the bolts that pass downwardly through the slots 56 and 156 engage with, and then are tightened into, respective threaded apertures in (or nuts held in position on or in) the base 16. If the length of the support frame is adjustable, the top surface of the base will normally contain a linear array of bolts or threaded apertures, so that a support frame having any one of a number of support frame lengths can be secured to the base 16.

Other, known, arrangements for clamping the support frame to the base may be used.

It should be appreciated that the mounting blocks 115 and 116 may be reversed. That is, the mounting block 116 shown in FIG. 3 may be used as the front mounting block, and the mounting block 115 of FIG. 3 may be used as the rear mounting block. It is also possible for other types of mounting blocks to be used in place of the blocks 115 and 116. Also, the mounting blocks may be made of another suitable rigid material, instead of steel, and one mounting block or more than two mounting blocks may be used to mount the support frame 40 on the base 16. The (or each) mounting block used may have any suitable shape, provided it can hold the support frame effectively, It may be a solid or a hollow structure. In addition,

-   a) only one clamping/adjusting screw 58 and only one     clamping/adjusting screw 158 may be used, or -   b) more than two clamping/adjusting screws 58 and more than two     clamping/adjusting screws 158 may be used, and -   c) alternatives to the “handles” 59 and 159 may be used to control     the clamping/adjusting screws (this comment concerning handles     applies to all adjusting screws illustrated in the accompanying     drawings).

The rear stock 11 of the rifle 10 is clamped in position by a pair of stock clamping members 21. As shown in FIGS. 4, 5 and 6, the stock clamping members 21 are disc-like in shape and are each mounted on bearings on a respective clamping member support which, in the illustrated embodiment, is an axle 22, about which they are able to rotate freely. (However, the stock clamping members 21 need not be disc-like, as shown, but may have any suitable peripheral shape, and they may be provided with bushes, ball joints, thrust bearing devices, or another suitable mounting arrangement which permits their rotation. In addition, to prevent movement of the gun due to the recoil effect, each stock clamping member 21 may be rigidly—that is, non-rotatably—affixed to its associated clamping member support (for example, by being welded to it).

Each axle 22 of the illustrated (prototype) embodiment is formed integrally with, or is attached to one end of, a respective threaded rod 23, which passes through an internally threaded horizontal aperture in a support block 25. Rotation of a handle 123 (or its equivalent) at the outer end of each rod 23 moves the inner end of the rod 23 (and thus also moves the associated axle 22 with its bearing and clamping member) towards or away from the inner end of the other rod 23 (and its associated axle 22, bearing and stock clamping member 21). Thus when a rifle is positioned on the sighting-in apparatus as shown in FIG. 1, the handles at the end of the rods 23 are rotated so that the stock 11 of the rifle 10 is clamped between the clamping members 21. The vertical face of each clamping member 21 (which may be annular, or any other suitable shape, and thus not extend over the entire clamping member) will normally be coated with a layer of rubber, neoprene, or a similar compressible and resilient material, to ensure that the rear stock 11 is not damaged when it is held firmly (that is, clamped) between the two stock clamping members 21.

In the embodiment shown in FIG. 6, each support block 25 is mounted at or near the forward end of a respective tilt arm 24 and is positioned above an associated side member 41 of the support frame 40. The other (rear) ends of the two tilt arms 24 are connected by a horizontal connecting bar 26. Each arm 24 is mounted on a respective pivot axle or stub axle 27 that passes through, or is mounted on, a transverse pivot block 28. The pivot block 28 is mounted securely on the support frame 40 and extends from the top of one side member 41 of the support frame to the top of the other side member 41. In the prototype apparatus, the pivot block 28 is of steel and is welded to the elongate side members 41 of the support frame. However,

-   a) other rigid materials may be used for the pivot block; -   b) joining methods other than welding may be used to mount the pivot     block on the support frame; -   c) the pivot block may have any suitable shape, and it may be a     solid or a hollow structure; and -   d) the support frame and pivot block may be formed integrally (for     example, as a cast or moulded unit).

The height of the clamping members 21 above the support frame 40 is controlled by threaded rods, namely (a) a threaded rod 20 which passes through a threaded aperture in a block welded to the horizontal connecting bar 26 (or which passes through a nut or nuts welded to that horizontal bar), and (b) two threaded rods 44, each of which passes through a threaded aperture in a block 144 welded to a respective one of the arms 24 (or which passes through a nut or nuts welded to the respective arm 24). The lower end of the threaded rod 20 bears against a transverse member of the support frame 40 (or, in the absence of a suitably positioned transverse member, a transverse plate or flat-topped bar which is supported on—typically, welded to—the top of the side members 41). The lower end of each rod 44 bears against the top surface of a respective side member 41 of the support frame.

Instead of a single threaded rod 20 mounted substantially centrally on the horizontal bar 26 (as shown in FIGS. 5 and 6), two threaded rods may be mounted on the horizontal bar 26, preferably symmetrically relative to the front-to-rear centre line of the apparatus and close to a respective arm 24. Alternatively, two threaded rods may be mounted on respective arms 24, near to the horizontal bar 26. With either of these two alternative arrangements, each of the two threaded rods will be used to provide fine adjustment of the position of its associated arm 24. In principle, more than two such threaded rods may be used but, it is believed, more than two such threaded rods are not necessary to produce effective sighting-in apparatus.

Another alternative arrangement is for the threaded adjusting rods 44 to comprise one or more bolts or threaded rods, passing through a transverse bar that is attached to the arms 24. Rotation of the, or each such, bolt or threaded rod will wind down, or up, the transverse bar, thus rotating the arms 24 about their pivot axes 27.

Other mechanically equivalent arrangements may be used instead of the threaded rod 20 (or multiple threaded rods), and instead of other threaded rods in the illustrated embodiments which are used for adjusting and/or clamping purposes. These alternative arrangements include electrically controlled, pneumatically controlled and hydraulically controlled arrangements.

When the illustrated sighting-in equipment is being used with a rifle, the front stock 12 (or the barrel 13) of the rifle 10 rests on the top of the central region of a transverse bar 30 (see FIGS. 7 and 8) that is supported by two posts 34 that pass through respective post-encircling members 32. Each post-encircling member 32 is welded to the outer vertical surface of a respective side member 41 of the support frame 40. Apertures 129 in the post-encircling members 32 and in the posts 34 enable pins (or bolts if these apertures are threaded) to be located within apertures 130 in the posts 34, and thus position the horizontal bar 30 at one of a number of pre-determined heights. A respective clamping bolt 33 may be used to prevent movement of each post 34, once the transverse bar 30 is positioned at the required height above the support frame 40.

A pair of blocks 31 (which, in the illustrated embodiment, have respective pads 35 stuck or otherwise fastened onto them) are mounted on top of the transverse bar 30. Each padded block 31

-   (a) may have its inner face substantially vertical over its lower     region, but with its upper inner face angled as shown, and -   (b) is connected to the inner end of a respective block adjusting     screw 37, and also to a threaded rod 135 which passes through slots     136 in the transverse bar 30 and projects below the transverse bar     30.

Each adjusting screw 37 passes through a respective threaded aperture of a block 39 (or through a nut or nuts) welded to the top surface of the transverse bar 30, adjacent to a respective end of the bar 30. When the sighting-in equipment is in use, rotation of a handle 38 at the outer end of an adjusting screw 37 moves the associated padded block 31 towards or away from the front stock (or the barrel) of the rifle, which will be resting on the top of the bar 30, until the inner, padded face of each block 31 touches, but does not clamp, the front stock 12 (or the barrel 13) of the rifle 10. When the padded blocks 31 are so positioned, the locking nuts 47 on the threaded rods 135 are tightened, to hold the padded blocks 31 firmly in position on the transverse bar 30. In a simplified version of this equipment, the adjusting screw 37 (with block 39) may be omitted, in which case manual adjustment of the blocks 31 to their required position is effected prior to clamping them in that position.

A strap, preferably of a non-resilient material, may be included as a bridge across the top of the blocks 31 to prevent excess lifting of the barrel of the gun being sighted-in, above the transverse bar 30, due to the recoil action when the gun is fired.

A layer 35 of a rubber compound, neoprene, or a similar compressible and resilient material will usually be bonded to the inner (opposed) faces of the blocks 31 to provide the padding on the blocks 31, and a similar layer 36 will usually be bonded to the central region of the top of the transverse bar 30, to minimise the possibility of damage to the front stock (or to the barrel) of the rifle when the equipment is used for sighting-in the rifle.

An alternative arrangement is to replace the padded blocks 31 with a single block having a generally V-shaped slot or groove in its upper surface. The slot or groove will have dimensions such that the barrel or front stock of the rifle being sighted-in will be positioned within, and be firmly held by, the side walls of this slot. Such a slotted block may be moveable along the horizontal bar 30 and clampable in a required position, or it may be formed integrally with the bar 30. Normally, a layer of padding will be provided within the slot, bonded to the side walls of the slot.

The blocks 31 shown in the accompanying drawings have their opposed faces constructed so that the lower part of each face is vertical and the upper part of the face is inclined away from the opposed face. With this arrangement, the blocks 31 can be used with the front stock (or barrel) of the gun resting on the horizontal transverse bar 30 (in which case, the blocks 30 may clamp the front stock in position), or they may be used with their vertical faces touching each other (in which case, the blocks 31 form a V-shaped slot or groove, in which the barrel of the gun—or the front stock—may be rested).

Engineers will appreciate that the transverse bar 30, the posts 34 (and hence the post-encircling members 32) need not-be fabricated, as shown in the accompanying drawings, from steel tubes of rectangular cross-section, but (a) could be made (for example) from steel tubing of circular or other cross-section, or from tubing or solid rods of a rigid material other than steel, having a rectangular, circular or other cross-section; or (b) could be a single, moulded part of the equipment of this invention.

The embodiment illustrated in FIGS. 1 to 8 of the accompanying drawings, and described above, is the present inventor's prototype of the invention. Some variations to and modifications of this prototype embodiment have been indicated already. Other variations and modifications may be made,

For example, all components of the apparatus that have not already been specified as capable of being produced by casting or moulding may be so produced.

In addition, the support frame 40 that is illustrated in FIGS. 1 to 8 may be replaced with a support frame (examples are shown in FIG. 9) having a single, central, elongate member 91 and one or more transverse members 42. If a support frame having a single elongate member 91 is used, a single post 32 may also be used, with a transverse bar 30 at the top of the single post 32 to support either a pair of padded blocks 31 or a single block having a V-shaped slot in its upper surface. The alternative realisations of the support frame shown in FIG. 9 are not exhaustive.

Also, a different type of mounting block, shown in FIG. 10, may be used instead of the mounting block 116. This different mounting block has a single spigot or post 101 extending upwardly from its centre. The post 101, when the apparatus of this invention is in use, is located within a circular aperture (the post 101 should be a close fit within this aperture) that is in the underside of a transverse member 42 of the support frame 40 (but which, instead, may be in the underside of the elongate member 91 if one of the support frame constructions illustrated in FIG. 9 is used). A variation of the mounting block shown in FIG. 10 is for the post 101 to be threaded and to be long enough to pass through the support frame and project above the top surface of the support frame. A nut may then be used to clamp the support frame to the mounting block.

If one of the support frame constructions illustrated in FIG. 9 is used, the “cradle” assembly of the mounting block 115 shown in FIG. 3 (that “cradle” assembly comprises plates 51, 52 and 53) either (a) will be omitted, or (b) will be duplicated, in which case the two “cradle” assemblies will be positioned on either side of the mounting block 115, so that the single elongate member 91 can be placed between the “cradle” assemblies.

Another alternative mounting block construction comprises a single, threaded, horizontal rod that passes through a threaded horizontal aperture in one (or both) of the elongate members 41 (or the elongate member 91 if one of the arrangements shown in FIG. 9 is used). Rotation of this single threaded rod will move the elongate member(s) to the right or to the left of its (their) “central” position.

A further alternative mounting block construction is shown in FIG. 11. This mounting block is a variation of the mounting block 115 shown in FIG. 3, and the reference numerals used in FIG. 11 indicate features which correspond to those in FIG. 3 having the same reference numerals. Engineers will appreciate the construction of the mounting block shown in FIG. 11 and further description of that mounting block is not necessary here.

Yet another alternative mounting block arrangement is with the front and rear mounting blocks constructed as a single entity, which is clamped onto the base 16. With this arrangement, only limited lateral adjustment of the support frame (when in position on the mounting block) is possible and lateral adjustment of the pointing of the gun being sighted in will be effected using only the gun supporting arrangements mounted on the support frame 40.

If the gun to be sighted-in fires high calibre ammunition, significant recoil will be experienced when the gun is fired. For such guns, the rear stock clamping members 21 may be modified to include a butt clamping strap which is connected to the threaded rods 23 and which passes behind the butt of the rear stock 11 of the gun. Such a butt clamping strap—preferably having a length which is adjustable—will assist in preventing recoil slip. Alternatively, or in addition, a block of wood (or other suitable material), preferably shaped to be a close fit around the butt of the rear stock, may be placed between the butt of the rear stock 11 and the pivot block 28 to prevent or minimise recoil slip.

For very powerful guns, the clamping members 21 and the threaded rods 23 may be replaced with a transverse threaded rod which passes through substantially vertical side plates which are rigidly mounted on the support frame, and also through the rear stock of the gun. Nuts (for example, wing nuts) on the transverse threaded rod will be tightened onto the rear stock (preferably with a resilient annular pad and a washer between the rear stock and each washer) to hold the rear stock rigidly in position on this threaded rod.

These alternative constructions are not exhaustive.

The above description of the apparatus or equipment constructed in accordance with the invention has concentrated on the sighting-in of a rifle or shotgun. It should be noted that, provided the length of the support frame is short enough, a pistol can be sighted-in using the same equipment. The rear stock clamping arrangement will clamp the handle of the pistol and the front stock (or barrel) locating means will be a barrel locating means only.

To perform the sighting-in of a gun, the invention may be used in an indoor shooting range, where there is no wind to affect the trajectory of a bullet or a charge of shot.

However, if the invention is used in an outdoor or open (long distance) shooting range, the sighting-in should be performed at a time when there is no wind or thermal air movement.

If the sighting-in is of a rifle (rifle 10 in FIG. 1), the apparatus will be set up as shown in FIG. 1 of the accompanying drawings. The support frame 40 will be mounted on the mounting blocks 115 and 116, which, in turn, are mounted on the base 16, and the rifle will be mounted on the support frame with the clamping members 21 holding the rear stock of the rifle. The base 16 will normally be positioned so that the barrel 13 of the rifle on the support frame 40 is pointing at the region in which targets are displayed. To aim the rifle at a target, the adjusting/clamping screws 58 and 158 on the mounting blocks 115 and 116 are adjusted to move the aim to the left or right, and the adjusting screw (threaded rod) 20 is rotated (after slacking off the adjustment screws 44) to move the aiming point up or down. If the rifle has a telescopic sight with cross hairs, the initial aim of the rifle is effected with the cross hairs vertical and horizontal, and with the intersection point of the cross-hairs or the “dot” on the target. Fine adjustment of the aim may then be effected using the side adjustment screws 44 in conjunction with the adjustment screw (threaded rod) 20.

The usual steps taken to aim a rifle on the prototype apparatus are:

-   1. Clamp the mounting blocks 115 and 116 to the base 16, and loosen     the clamping/adjusting screws 58 and 158. -   2. Position the support frame on the mounting blocks 115 and 116 and     adjust the clamping/adjusting screws 58 and 158 until the vertical     cross-hair or dot of the telescopic sight of the gun (or its open     barrel sight) has been moved to the right or left (as required) and     is approximately over the range target. -   3. Loosen all adjustment screws or bolts 44 and the threaded rod (or     rods) 20. -   4. Adjust the arms 24 about their pivot points 27 using the threaded     rod (or rods) 20, until the horizontal cross-hair (or “dot”, or open     barrel sight) is above the target. -   5. Adjust the screws or bolts 44 so that they bear against the top     surface of the side members 41 of the support frame 40, or against     the top surface of a transverse member 42 (or, in the absence of a     suitably positioned transverse member, a transverse plate or     flat-topped bar which is supported on—typically, welded to—the top     of the side members 41) of the support frame 40. -   6. Tighten each screw or bolt 44 and rod(s) 20 individually to move     the cross-hairs across at angles, and up and down, relative to the     target, until the intersection of the cross-hairs (or the “dot” or     the open barrel sight) is on the target.

When the cross hairs (or the “dot” or open barrel sight) of the rifle sight are on the target, the rifle is properly aimed. A first bullet will now be fired.

The distance between the intended point of impact of the first bullet on the target and its actual point of impact will be noted.

If the distance between the actual point of impact of the bullet and the point at which the rifle was aimed is large, the rifle sights may be adjusted until the rifle-sight is on the actual point of impact on the target. The sighting-in procedure should then be started again with the firing of a new first bullet.

If the distance between the actual point of impact of the first bullet and the point at which the rifle was aimed is not large, the mounting of the rifle on the support frame and the mounting of the support frame on the base is not changed, but the sights of the rifle (whether telescopic sights or open sights) are adjusted until they show that the rifle is aimed at the actual point of impact of the bullet on the target. The rifle is then fired again. The second bullet should impact on the target at substantially the same point as the first bullet struck it. If this is the case, the rifle is now sighted-in.

If there is a significant difference between the intended point of impact of the second bullet (which is, of course, the actual point of impact of the first bullet) and its actual point of impact, that will be probably be due to air movement (caused by wind, humidity changes, or thermal activity over the range), or to variation in the cartridge loading, or the use of inferior ammunition (that is, ammunition which is not suitable for the rifle that is being sighted-in). In this situation, the sighting-in procedure should be repeated in still air, or a third bullet should be fired to check the sights of the rifle and the adjustments that have been made to the aiming of the rifle.

A similar procedure will be used for the sighting-in of a scoped pistol.

When sighting-in a shotgun, it is the centre of the group of points of impact of shot from a cartridge that is used as the intended point of impact. Thus, knowing the points of impact, the distance from the target, and the type of cartridge used, it is possible to adjust the aiming of the shotgun to put the centre of the group of shot on the centre of the target.

If a high powered, scoped, centre fire rifle, or a shotgun, is being sighted-in and the cross-hairs of the riflesight move due to the recoil action when the first bullet is fired, the grip of the rear stock clamping members 21 should be increased, or a block of wood (or other suitable material) should be placed between the butt of the stock 11 and the pivot block 28 to prevent recoil slip, and the rifle should be realigned using the adjustment screws or bolts 44 and the threaded rod or rods 20, or the adjustment screws 58 and 158 (until the cross-hairs of the gunsight are again on the intended point of impact on the target). The sighting-in procedure should then be started again with the firing of a new first bullet.

When using a centre fire rifle, the accuracy of the rifle is affected by the cartridges used. Different cartridges have differing powder type, powder charge capacity, projectiles, grains and weights. (The rifle configuration and variations in the ammunition charge are also factors that affect the shooter's accuracy with the rifle.) Thus, again, a shooter should experiment with different ammunition types and cartridge loadings to ascertain which is the most appropriate ammunition for the rifle. When testing different ammunition types, five shots from each type should be fired at respective target sheets. The resultant groupings on the targets will show which ammunition is the one to use with the rifle (the closer the grouping, the more suitable the ammunition is for use with the rifle).

Once a rifle has been sighted-in, a shooter, when competing in an event at a rifle range, can (1) fire a test shot with the rifle aimed at the centre (the bull) of a practice target, (2) note the difference between the intended point of impact of the bullet and its actual point of impact, and (3) use this information to adjust the point at which the rifle should be aimed when shooting at a competition target. If the competition is being held in an open air range, the shooter should fire at the competition target as soon as possible after the practice shot, so that the possibility of a change in the wind speed and/or direction occurring after the practice shot (both changes will affect the trajectory of a bullet from a rifle) is minimised. If the rules of the competition permit it, a sighting or practice shot should be made before each shot at a target of the competition. 

1. Apparatus for use in sighting-in of a gun, said gun having a barrel, a rear stock and (if the gun is a rifle) a front stock; said apparatus comprising: a) a generally elongate support frame having a front end and a back end; b) a base on which said support frame is mounted; c) front stock (or barrel) locating means mounted on said support frame at or near the front end thereof; said front stock (or barrel) locating means comprising a horizontal bar supported above, and extending in a direction transverse to the elongate direction of said support frame, and restraining means mounted on said bar to prevent sideways movement of said front stock (or barrel); d) rear stock clamping means mounted on said support frame at or near the back end thereof; said rear stock clamping means comprising a pair of stock clamping members, each stock clamping member having a substantially vertical surface which is opposed to the substantially vertical surface of the other stock clamping member; each stock clamping member being adapted to be moveable laterally relative to the elongate direction of the support frame, so that, when the sightingin apparatus is in use, said vertical surfaces may be moved to contact respective side faces of the rear stock of a rifle or a shotgun, or to contact respective side faces of the handle of a pistol or similar gun, which is mounted on said apparatus; each said stock clamping member being mounted on a respective horizontal clamping member support, which is substantially at right angles to the substantially vertical surfaces of said clamping members; each of said clamping member supports being mounted on an axle at the end of a respective, substantially horizontal, threaded support rod; each said threaded support rod passing through a respective, internally threaded, substantially horizontal, aperture in a rod support block that is mounted at or near the forward end of a respective one of a pair of tilt rods; each said tilt rod being mounted for at least partial rotation about a respective tilt axis; and e) gun tilting means for raising or lowering the rear stock clamping members relative to the top of the support frame, thereby to lower or raise the front of the barrel of the gun relative to its rear stock (if a rifle) or its handle (if the gun is a pistol); said gun tilting means comprising means to rotate said tilt rods about said tilt axes.
 2. Apparatus as defined in claim 1, in which said tilt axes are established by an axle or a pair of axles mounted on a pivot block that is mounted on said support frame and said gun tilting means comprises a plurality of adjustable threaded rods each having a substantially vertical screw axes; said adjustable threaded rods being also operable to hold said tilt arms rigidly in required positions relative to said axle block.
 3. Apparatus as defined in claim 2, in which said adjustable threaded rods comprise two adjustable threaded rods, each mounted on a respective one of said tilt arms, forward of said pivot block, and a third adjustable threaded rod mounted on a horizontal connecting bar which connects the tilt arms rearward of said pivot block.
 4. Apparatus as defined in claim 1, in which a stock butt clamping strap is attached to said threaded support rods, or to said rear stock clamping members.
 5. Apparatus as defied in claim 1, in which said restraining means comprises a pair of blocks which are moveable along the top of said horizontal bar and are clampable thereto.
 6. Apparatus as defined in claim 5, in which each of said blocks has an inner face which is padded.
 7. Apparatus as defined in claim 5, in which at least the central portion of the top of said horizontal bar is covered with a layer of a resilient material.
 8. Apparatus as defined in claim 1, in which said restraining means, comprises a block mounted on said horizontal bar; said block having a generally V-shaped slot in the top surface thereof; said slot having dimensions which permit said barrel or said front stock to be firmly positioned within said slot.
 9. Apparatus as defined in claim 8, in which said block is moveable along the top surface of said horizontal bar and is clampable to said horizontal bar.
 10. Apparatus as defined in claim 8, in which the inner faces of said slot are padded.
 11. Apparatus as defined in claim 1, in which the height of said horizontal bar above said support frame is variable.
 12. Apparatus as defined in claim 1, in which each said stock clamping member is rigidly attached to its associated clamping member support.
 13. Apparatus as defined in claim 1, in which each said stock clamping member is attached to its associated clamping member support for rotation thereabout.
 14. Apparatus as defined in claim 1, in which said support frame comprises a pair of elongate side members and at least two transverse members connected at each end thereof to said side members.
 15. Apparatus as defined in claim 1, in which said support frame comprises two sub-frames, each sub-frame having a pair of elongate side members connected by at least one transverse member, said transverse members of said sub-frames being of equal length, said side members of each sub-frame being parallel to each other, and either a) each side members of one sub-frame is hollow or has a central elongate cavity extending over at least part of its length, and the side members of the other sub-frame are dimensioned to fit within the hollow regions or within the elongate cavities of respective side members of said one sub-frame; respective retaining means being provided to hold each side member of said other sub-frame within a hollow region or cavity of a side member of said one sub-frame; or b) the side members of each of said sub-frames are hollow or have a respective central cavity extending over at least part of the length thereof; and a pair of frame support rods are inserted into respective co-linearly aligned side members of the sub-frames; retaining means being provided to hold each aligned side member of the sub-frames firmly in position over an end of its associated frame support rod.
 16. Apparatus as defined in claim 14, in which said support frame is mounted on a pair of mounting blocks positioned, respectively, one towards the front end of said support frame and the other towards the back end of said support frame, each mounting block being rigidly secured to said base.
 17. Apparatus as defined in claim 16, in which one of said mounting blocks is constructed with a cradle into which a transverse member of said support frame may be positioned; said cradle comprising: a) a horizontal plate having a forward edge and a rearward edge; b) a first planar, vertical plate extending upwards from said forward edge; c) a second planar, vertical plate extending upwards from said rearward edge; and d) at least one clamping member operatively connected to one of said vertical plates, to clamp a transverse member of said support frame between said vertical plates.
 18. Apparatus as defined in claim 17, in which said cradle is mounted on an elongate transverse block member, with the planes of said vertical plates parallel to the elongate direction of said transverse block member; a third planar vertical plate and a fourth planar vertical plate extending upwards from respective ends of said transverse block member, the planes of said third and fourth vertical plates being perpendicular to the elongate direction of said transverse block member; said third and fourth vertical plates being spaced apart a distance greater than the distance between the outer edges of said side members of said support frame; one (or a respective) clamping member being operatively connected to said third or (or and) said fourth vertical plate, to clamp said side members of said support frame between said third and fourth vertical plates.
 19. Apparatus as defined in claim 18, in which a planar clamping plate extends horizontally from the lowermost point of said transverse block member; an elongate slot being formed in said clamping plate, through which a bolt extending from or into said base may pass.
 20. Apparatus as defined in claim 18, in which a second of said mounting blocks comprises a second elongate block member mounted on said base with the elongate direction thereof being transverse the fore-and-aft direction of said apparatus; a fifth planar vertical plate and a sixth planar vertical plate extending upwards from respective ends of said second transverse block member, the planes of said fifth and sixth vertical plates being perpendicular to the elongate direction of said second block member; said fifth and sixth vertical plates being spaced apart a distance greater than the distance between the outer edges of said side members of said support frame; one (or a respective) clamping member being operatively connected to said fifth or (or and), said sixth vertical plate, to clamp said side members of said support frame between said fifth and sixth vertical plates.
 21. Apparatus as defined in claim 18, in which a second of said mounting blocks comprises a second block member mountable on said base, a post extending vertically upwards from the top surface of said second block member, said post being dimensioned to be a close fit within an aperture in the underside of a transverse member of said support frame.
 22. Apparatus as defined in claim 21, in which (a) said post has a length sufficient to pass upwards through, and extend above, said support frame; and (b) at least the top region of said post is threaded, so that a nut thereon may be used to hold said support frame securely on said second block member.
 23. Apparatus as defined in claim 20, in which a second planar clamping plate extends horizontally from the lowermost point of said second block member; an elongate slot being formed in said second clamping plate, through which a bolt extending from or into said base may pass.
 24. Apparatus as defined in claim 1, in which said support frame comprises a single elongate member mounted on said base with its elongate direction in the fore-and-aft direction of said apparatus, and at least one transverse member extending across said single elongate member.
 25. Apparatus as defined in claim 1, including a transverse strap member mounted above said front stock (or barrel) locating means, to restrict the upwards movement of the barrel of said gun as a result of recoil when a bullet or shot cartridge in said gun is fired. 